Novel peptides and pharmaceutical compositions comprising the same are disclosed. Conjugated compositions peptides linked to detectable agents and/or cytotoxic agents are disclosed. Method of detecting tumors that have p185 on tumor cell surfaces are disclosed. Methods of preventing transformation of a normal cell into a tumor cell in an individual at risk of developing a tumor having tumor cells which have p185 on their surfaces are disclosed. Methods of treating an individual who has cancer characterized by tumor cells that have a p185 on their cell surfaces are disclosed.